The present invention pertains to a process for the preparation of aromatic polymers and more particularly pertains to a process for the preparation of poly(benz(ox, imid, thi)azole) polymers.
Current methods of poly(benzoxazole), poly(benzimidazole), and poly(benzthiazole) formation involve the condensation of bis(o-aminophenols, amines or thiols) and aromatic diacid derivatives. This presents the shortcoming of a limited variety of available diacids and/or extra synthetic steps necessary to convert the diacid into a suitable derivative. In many cases the derivative is a diacid chloride which is hydrolytically unstable. In some of the methods, phenyl esters are used as the diacid derivatives. During polymerization this leads to the release of free phenol which is toxic.
Japanese Kokai 123823, published May 16, 1989, and Yoneyama et al, Macromolecules, Vol. 21, 1988, pp. 1908-1911 disclose the use of a Heck carbonylation reaction in the preparation of low molecular weight polyamides. U.S. Pat. Nos. 4,933,419; 4,933,466 and 4,933,467; and 4,933,468 disclose methods which utilize Heck reactions to produce esters, imides, and imide-amides, respectively. U.S. patent application Ser. No. 07/591,308, filed Oct. 1, 1990, and commonly assigned with this application, discloses use of the Heck carbonylation reaction to produce aryl benz(ox, imid, thi)azoles. Potts, Comprehensive Heterocyclic Chemistry, Vol. 6, pp 321-322 (1989) teaches cyclization of a precursor to provide 2-substituted benzothiazoles.
It is therefore highly desirable to provide an improved method for the preparation of poly(benz(ox, imid, thi)azole) polymers.
It is also highly desirable to provide an improved method for the preparation of poly(benz(ox, imid, thi)azole) polymers, which utilizes a Heck carbonylation and coupling reaction of aryl dihalides and bis(o-aminophenols, amines and thiols) rather than the condensation of bis(o-aminophenols, amines or thiols) and aromatic diacid derivatives.
It is also highly desirable to provide an improved method for the preparation of poly(benz(ox, imid, thi)azole) polymers, which avoids the use of hydrolytically unstable diacid chlorides.
It is also highly desirable to provide an improved method for the preparation of poly(benz(ox, imid, thi)azole) polymers, which avoids the use of phenyl esters as the diacid derivatives and the release of free phenol during polymerization.
It is finally highly desirable to provide an improved method for the preparation of poly(benz(ox, imid, thi)azole) polymers which provides all of the above desired features.